Grain conditioning apparatus



Sept. 12, 1961 E. F. EWING 2,999,676

GRAIN CONDITIONING APPARATUS Filed June 1, 1959 PLENUM AIFZ CHAMBEQ A Z!M 13 24 INVENTOR.

2,999,676 GRAIN CONDITIONING APPARATUS Ewell F. Ewing, 133 S. th St.,Beech Grove, Ind. Filed June 1, 1959, Ser. No. 817,395 3 Claims. (Cl.263-19) This invention relates generally to grain conditioning apparatusand in particular to a means for introducing heat directly into the airstream flowing through a tube or housing with minimum heating of thecentral core area of the housing.

Grain, when harvested, normally has a moisture content considerably inexcess of the optimum moisture content for suitable storage. The use ofartificial heat drying of the grain in batch or continuous flow prior toplacing the grain in storage has been widespread in conditioning grain.Another process used in drying grain has been the drying of the grain tothe proper storage moisture content directly in the storage bin byadding supplemental heat to the air stream to thereby retain therequired relative humidity of the air circulated through the grainindependently of variations in relative humidity of the incoming air.Apparatus for this latter type of grain conditioning process has usuallyincluded an air moving fan and, positioned upstream of the fan, aheating means such as a gas burner or the like. The heating means isconventionally controlled by a fixed-setting humidistat located in theair chamber. In the past such apparatus has been characterized by theintroduction of air heated by the burner at the central core area of thehousing through which the conditioned air flows. Since the air streaminducing fan and its driving motor are customarily located in thehousing with the axis of the fan and motor shaft coinciding with theaxis of the housing, most of the air flow through the tubular housingoccurs in an annular area adjacent the housing wall. Introduction ofheated air at the central core area of the housing therefore results insomething less than optimum mixing of the heated and unheated air and,further, tends to raise the temperature of the fan-driving motor toundesirably high levels.

It is a primary object of the present invention, therefore, to providean apparatus for drying grain in storage in which supplemental heat, inthe form of heated air, is added directly to the air stream so as toobtain a high degree of mixing of the heated air within the air streamwithout subjecting the fan motor to undesirably high temperature air.

A further object of the present invention is to provide an apparatus ofthe type referred to which requires a minimum of installation space.

A further object of the present invention is to provide an apparatus ofthe type referred to which includes a tub ular housing having an airstream-inducing fan and its drive motor mounted axially therein, andmeans for introducing heated air directly into the air stream whilemaintaining a minimum temperature rise of the motor and the housingwalls.

The full nature of the invention will be understood from theaccompanying drawings and the following description and claims:

FIG. 1 is a front view of an apparatus embodying the present invention.

FIG. 2 is a side view, partially in section, of the apparatus shown inFIG. 1.

Referring to the drawings, the apparatus includes a tubular housingmember 10 having an open end 11. The opposite end of the tubular memberis fitted with a flexible conduit 12 by means of a conventional hoseclamp 13, the flexible conduit communicating with the plenum air chamberof a conventional, perforated floor type grain drying bin (not shown).Supported axially within the ice tube is a multi-bladed fan whose blades14 extend from a hub 16 driven by an electric motor 17 supported bysuitable brackets (not shown) within the tube. The rotation of thedrying fan is such as to draw air through the open end of the tube anddischarge it into the grain drying bin.

The marginal area of the tube 10 carries an outwardly flanged ring 18whose peripheral flange is apertured to receive spaced studs 20. Thestuds extend rigidly from an annular member 19 and by means of spacers20a and nuts 26b serve to rigidly mount member 19 upon the open end 11of the tube and in spaced relation thereto. The member 19 is formed ofsheet metal and rolled to form a generally annular tubular configurationwhich is spiral shaped in cross-section. The marginal areas 22 and 23 ofthe member 19 overlap and are spaced from each other at the innercircumference of the heat exchange member, with the inner diameter ofthe marginal area 22 being equal to the inner diameter of the tubularhousing 10. The spaced marginal areas 22 and 23 thus provide an annularpassage 24 which opens inwardly toward the end 11 of the tube 10, themarginal area 22 also providing a Vcnturi entry for the tube.

As may best be seen in FIG. 1, the member 19 is formed to provide aperipherally extending intake tube 26, an internal plate 27 serving todirect gases passing through the tube 26 in a controlled trajectoryperipherally around the interior of the member 19. By means of a flangedconnection 28 the tube 26 communicates with the interior of a burnerassembly 29.

The burner assembly itself forms no part of the present invention and isnot described in complete detail herein. As shown in FIG. 1, it mayinclude a housing 31 having a gas burner 32 disposed therein. The gasburner may be monitored by a conventional thermocouple-operated pilotsafety system indicated schematically at 33. The pilot burner 34 may beignited through the grilled end 36 of the burner housing. A junction box37 provides connection into the burner control valve energizing circuitfor a conventional humidity responsive control or humidistat indicatedgenerally at 38. The humidistat is preferably located in the plenum airchamber of the grain drying bin, indicated diagrammatically at 40 inFIG. 1, and responds to a predetermined increase in humidity of the airentering the grain drying bin to energize the control valve for theburner 32.

Adjacent the entrance to the tube 26 there is provided a booster fanindicated generally at 39 which may be electrically motor driven, thedriving motor being energized whenever burner 32 is ignited. Aconventional sail switch may be provided which is responsive tooperation of the drying fan to assure that the burner 32 cannot beignited unless the drying fan 17 is in operative condition. It will beunderstood that an air stream monitoring device other than a sail switchmight, of course, be utilized to assure that the drying fan is operativebefore the burner is ignited.

In operation, the drying fan normally runs continuously, moving airthrough the tube 10 and into the grain drying bin. When the relativehumidity of the incoming air is above, for example, 55%, the humidityresponsive control 38 will cause the burner 32 to be ignited. Thebooster fan 39 serves to force the hot products of combustion into theheat exchange member 19 and move them in a controlled trajectory aroundthe interior thereof. The hot gases within the heat exchange member exitthrough the annular passage 24 and enter the air stream in the tube 10adjacent the outer peripheral margin thereof. With the fan and motor 17mounted axially in the tubular housing the major portion of the air flowthrough the housing 10 occurs in a peripheral band adjacent the housingwall. The introduction of the high temperature gases through the passage24 at this peripheral, maximum flow area, provides excellent mixing ofthe hot gases in the air stream. The introduction of the hot gases intothe air stream is also selective in that the air entering the tubularhousing at its central core area is left substantially free of hotgases, and this portion of the air stream, flowing past the motor 17prevents an undesirable temperature rise of the motor. Spacing themember 19 outwardly from the end 11 of the housing permits theaspiration of unheated air through the space separating these elementsas indicated by arrows in FIG. 2. This relatively cool air sweeps alongthe inner surface of the housing and prevents the housing walls fromattaining an elevated temperature. Loss of heat by radiation from thehousing is thus minimized and a safety factor is provided in preventingthe occurrence of high temperature exterior surfaces on the apparatus.

When the relative humidity of the air entering the grain drying binisagain reduced to a value below the control point, the burner 32 is shutdown and the drying fan continues to operate, moving unheated air intothe bin. When the relative humidity of the air entering the bin againreaches a value above the control point, the heating or humidityreducing cycle is repeated.

From the foregoing it will be evident that the trajec tory-type heaterprovided by the contour and placement of the member 19 results in theintroduction of the hot gases into the air stream at a point such as toprovide good mixing without subjecting the motor 17 to elevated airstream temperatures. The unheated air induced to flow through the spacebetween the member 19 and the tube end 11 limits the temperature rise ofthe housing. The dimensioning of the inner diameter of the marginal area22 so as to be at least equal to the inside diameter of the tubularhousing 10 permits the hot gases to be introduced into the tubularhousing without restricting the air flow therethrough and thus does notadversely afiect the capacity of the apparatus.

While the invention has been disclosed and described in some detail inthe drawings and foregoing description, they are to be considered asillustrative and not restrictive in character, as modifications mayreadily suggest themselves to persons skilled in this art and within thebroad scope of the invention, reference being had to the appendedclaims.

The invention claimed is:

1. Apparatus for introducing heated air into a grain storage bincomprising a cylindrical tube, a fan and an electric drive motortherefor mounted Within said tube coaxially therewith for moving airthrough the tube, the air outlet end of said tube being adapted tocommunicate with the grain storage bin, an annular tubular member havinga generally spiral cross-sectional configuration in a plane parallel tothe axis of said tube and supported on said tube in spaced relation withthe air inlet end thereof, said annular member having spaced,overlapping marginal areas disposed at the inner circumference thereof,the diameter of said annular member at its inner circumference being atleast equal to the inside diameter of said tube, said spaced marginalareas providing an annular passage communicating with the interior ofsaid annular member, and means for introducing hot gases under positivepressure peripherally into said annular member, whereby the hot gasesenter said tube only at the peripheral area thereof and unheated air isdrawn into said tube through the space between said tube inlet end andsaid annular member thereby moderating the temperature rise of said tubeand said drive motor.

2. Apparatus for introducing heated air into an enclosure comprising atube, a fan and an electric drive motor therefor mounted within saidtube coaxially therewith for moving air through the tube, the air outletend of said tube'being adapted to communicate with said enclosure, anannular tubular member having a generally spiral cross-sectionalconfiguration in a plane. parallel to the axis of said tube andsupported in spaced relation with the air inlet end of said tube, saidannular. member having spaced, overlapping marginal areas disposed atthe inner circumference thereof, the diameter of said annular member atits inner circumference being at least equal to the inside diameter ofsaid tube, said spaced marginal areas providing an annular passagecommunicating with the interior of said annular member, and means forintroducing hot gases under positive pressure peripherally into saidannular member, whereby the hot gases enter said tube only at theperipheral area thereof and unheated air is drawn into said tube throughthe space between said tube inlet end and said annular member therebymoderating the temperature rise of said tube and said drive motor.

3. Apparatus for introducing heated air into a grain storage bincomprising a tube, a fan and an electric drive motor therefor mountedwithin said tube coaxially therewith for moving air through the tube,the air outlet end of said tube being adapted to communicate with thegrain storage bin, an annular tubular member having a generally spiralcross-sectional configuration in a plane parallel to the axis of saidtube and supported adjacent the air inlet end of said tube, said annularmember having spaced, overlapping marginal areas disposed at the innercircumference thereof, the diameter of said annular member at its innercircumference being at least equal to theinside diameter of said tube,said spaced marginal areas providing an annular passage cornmunicatingwith the interior of said annular member, and means for introducing hotgases under positive pressure peripherally into said annular member,whereby the hot gases enter said tube only at the. peripheral areathereof thereby moderating the temperature rise of. said drive motor.

UNITED STATES PATENTS References Cited in the file of this patent591,966 Halliwell Oct. 19, 1897 2,477,584 De Zubay Aug. 2, 19492,815,982 Bleamaster Dec. 10, 1957 2,889,142 Ammann June 2, 1959

